A marker for health assessment, and an application thereof, relating to the field of medical test. An application of a marker identification reagent in preparation of a reagent for measuring the health of a mammal, comprising: (1) measuring a marker in a test sample, wherein the marker is the level of 8-oxoGsn; and (2) comparing the marker with a reference, wherein the difference between the marker and the reference is used for assessing the health condition of the subject. According to the invention, comprehensive health condition assessment is performed on a subject by means of a simple clinical examination method, and the health condition and health laws of people can be obtained timely and quickly; compared with conventional medical test methods, the invention has remarkable advantages in detection and early warning of sub-health, disease treatment effect monitoring, and psychological emotional state detection in the field of health service management.